Determination of Nitrogen fertilizer requirement in Bambara groundnut(Vigna Subterranea (L.)Verdc.)

Abstract

This study was carried out during the 1993 /94 cropping season at the University of Zambia (UNZA) Farm and Lusitu Sub-Research Station which are situated in Agroecological Zones II and I (medium and low rainfall), respectively. The objective was to determine the nitrogen fertilizer requirement for Bambara groundnut using accessions of different yielding potential. A split plot design was used, with six accessions (ZAVs 3, ZAVs 7, ZAVs 120, ZAVs 6, ZAVs 5 and ZAVs 8) and five nitrogen levels (0, 15, 30, 45 and 60 kg N/ha) as main and sub plots, respectively. The accessions were chosen on the basis of yielding potential, i.e., low (ZAVs 6 and ZAVs 8), medium (ZAVs 7 and ZAVs 120) and high (ZAVs 3 and ZAVs 5) as judged by results of a study carried out during the 1992/93 season. The yield parameters measured were: days to 50 % flowering, days to maturity, number of leaves per plant, number of stems per plant, number of branches per plant, number of nodes per plant, number of pods per plant, plant spread, plant height, 100 seed weight and grain yield. However, due to severe moisture deficit, yield was measured at UNZA Farm only. The total nitrogen content of leaves at pod formation and in the soil after harvesting were also measured. The results indicated that at both locations, nitrogen fertilizer did not have any effect on yield and all yield attributes measured except plant spread and number of pods per plant. However, accessions responded differently to N fertilizer, but this was true for ZAVs 7 only. Highest yields were obtained with 15 kg N /ha (321 kg/ha)grain, while the lowest was obtained with 30 kg N/ha (65.70 kg/ha) while other treatments had similar. Yield was V positively correlated with number of leaves per plant, plant height and the number of pods per plant. The nitrogen fertilizer levels did not have any significant effect on plant N content as well as on N content of the soil after harvesting. Location had an effect on some yield attributes, i.e. , plants at UNZA Farm were taller and wider with a higher number of stems than those at Lusitu. Plants at Lusitu had 3.66 % N content which was higher than UNZA Farm's 3.13 % N. The experiment was seriously affected by moisture and temperature stress. The average yield at UNZA farm was 183 kg/ha. A concrete conclusion cannot be made from this experiment. It is therefore recommended that the experiment be repeated under a controlled environment in order to get a more accurate and reliable conclusion